cum cv. Virginia 1.06% TMV-IL6ER PVX-IL6ER 7.78% 0.65% 4.79% 0.09% 0.40% Standard deviation in brackets. doi:10.1371/journal.pone.0048938.t003 Expression of Human IL6 in Tobacco Transformation type Construct Cultivar Plant organ Expression level stable pLH-IL6ER N. tabacum cv. Geudertheimer leaf 0.14% stable pLH-IL6ER N. tabacum cv. Geudertheimer seed 0.12% transient transient Lck Inhibitor supplier pICH29912-IL6ER pICH29912-IL6ER N. benthamiana N. tabacum cv. Geudertheimer leaf leaf 7.78% 0.65% transient pICH29912-IL6ER N. tabacum cv. Virginia leaf 1.06 doi:10.1371/journal.pone.0048938.t004 14 Expression of Human IL6 in Tobacco cultivation of transgenic plants on an agricultural scale would attract a lower regulatory burden than large-scale spraying with recombinant bacteria, and the seeds can be sterilized before processing, making them more attractive for the production of biotherapeutics with respect to GMP compliance. The best performing plants carry a single transgene locus, which allows the straightforward propagation of homozygous transgenic lines. These aspects of upstream production become even more relevant in relation to the downstream processing, which represent approximately 80% of the overall production costs. The ease and efficiency of product recovery differs drastically between cultivars or organs used for expression. Hence, upon purification the yield might be drastically different compared to the expression achieved in planta with a strong impact on the process economics. 16722652 Seeds are characterized by a simple metabolic profile and low proteolytic activity, facilitating downstream purification efforts, whereas leaf tissue produces cross-purifying secondary metabolites and recombinant proteins are highly instable upon harvest.
As key regulators for gene expression at post-transcriptional levels, microRNAs are a class of endogenous noncoding RNAs transcribed by RNA polymerase II with a size range of,22 nt; they are processed from larger hairpin structures–known as pri- and pre-miRNAs–by two specialized proteins, namely Drosha and Dicer . Mature miRNAs are incorporated into the RNA-induced silencing complex with the Piwi/Argonaute protein family to exert their functions, whereas their opposite strands, known as miRNAs, are scrapped. Previous discoveries suggested that the strand whose 59 end is less stably paired as miRNA:miRNA duplex is preferentially packaged into RISC. Similar to lin-4 and let-7 of Caenorhabditis elegans, the majority of miRNA genes are transcribed as independent transcriptional units albeit a few of them were found in introns of premRNAs and co-expressed with their host genes. A large fraction of miRNAs are conserved among closely-related species, and many even have homologs in distant species. For instance, more than 
a third of miRNAs found in C. elegans have homologs in humans, suggesting that they have important functions that are evolutionarily-conserved. miRNA genes are sometimes observed as clusters frequently transcribed as single polycistronic transcript, implying that they may share common functional relationships. Since lin-4 and let-7 were found microRNAs in Silkworm to regulate development in C. elegans, ample reports have suggested 8941386 that miRNAs play significant regulatory roles under physiological and pathological conditions in plants, flies, fishes, and mammals. Although animal miRNAs tend to show imperfect base-pairing in 39 untranslated regions of their target transcripts, a 7-nt seed sequence starting from
